JPS63276853A - Micro-wave plasma processing device - Google Patents

Abstract

PURPOSE:To enlarge the processing area and enhance thereby the processing efficiency by furnishing a plasma production chamber with a portion, in which the section area of the chamber increases approx. continuously from the opening of a waveguide path toward an ion drawout device. CONSTITUTION:A vessel 16 is inscribed with permanent magnets 15a-15d. This causes the magnetic flux density near the inner surface of the vessel 16 to be approx. equal on the microwave incident side and ion drawout electrode 17 side, and such a magnetic flux density can be obtained as meeting the cyclotron resonance (ECR) condition at the points approx. at the same distance from the wall of vessel 16. This allows enlargement of the plasma production range gradually from the microwave incidental side toward the ion drawout electrode 17, which should increase the ion drawout area. Thus the processing area will be enlarged to lead to enhancement of the processing efficiency.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a microwave plasma processing apparatus that performs surface treatment on a sample using plasma generated by the interaction of microwaves and a magnetic field.

[Conventional technology]

Plasma is generated using microwave power, a solenoid coil is placed around the plasma generating chamber, and the magnetic field generated by the solenoid coil and the cyclotron movement of electrons due to the electric field of the microwave are used to further improve the plasma generation efficiency. Microwave plasma processing equipment that increases the
For example, the outline will be explained using figures.

FIG. 8 is a sectional view of a conventional microwave plasma processing apparatus. In the figure, l is a microwave oscillator that generates microwaves, 2 is a waveguide that transmits the microwave power generated by the microwave oscillator 1, 3 is a container connected to the waveguide 2, and 4
Reference numeral 5 indicates a plasma generation chamber formed by the container 3, 5 an entrance window for introducing microwaves into the plasma generation chamber 4, and 6 the plasma generated within the plasma generation chamber 4. 73.7bi
A solenoid coil is provided outside the container 3, 8 is an ion extracting magnetic pole for extracting ions in the plasma 6, and 9 is a processing device for performing various treatments using the extracted ions. 1 () is a sample supported by a hoist (not shown) in the processing device 9, 11 is an ion extracted by the ion extraction device 8, and 12 is a vacuum evacuation device that evacuates the inside of the plasma generation chamber 4 and the processing device 9. It is a device.

When a predetermined gas is introduced into the plasma generation chamber 4 while microwaves are being applied, the gas is turned into plasma by the microwaves, and the electrons present in the plasma 6 are transferred to the solenoid coil 7a.

Cyclotron motion is performed under the influence of the magnetic field formed by 7b. Due to the cyclotron movement of the electrons, the electrons collide with neutral particles such as molecules and atoms in the container 16, ionizing the particles and generating ions. By repeating such operations, the plasma of the introduced gas is steadily promoted, and the plasma generation efficiency is improved. 2 assigned for industrial use by the Radio Law as a microwave frequency
, 45GH2, the magnetic flux density that satisfies the cyclotron resonance (ECR) conditions for generating cyclotron motion in electrons is 0.0875 Tesla.

The ions existing in the plasma 6 thus formed are extracted by an ion extraction device 8 (consisting of a plurality of magnetic poles), become an ion jaw 11, and are introduced into the processing device 9. 11, the sample 10 is subjected to milling, etching, and other treatments.

[Problem that the invention seeks to solve]

By the way, in the above-mentioned microwave plasma processing apparatus, when processing such as milling and etching on the sample 10 is completed, the sample 10 is taken out, replaced with an untreated sample, and the same process is repeated again. It will be done. Therefore, in order to improve the processing efficiency (productivity efficiency), it is necessary to process more samples at one time, and for this purpose, the cross-sectional area of the plasma generation chamber 4 may be increased. However, in order to obtain a good coupling degree of the microwave incident on the plasma generation chamber 4, the cross-sectional area of the plasma generation chamber 4 must be selected to approximate the cross-sectional area of the microwave waveguide 2. As a result, the processing efficiency of the sample 10 could not be improved by increasing the cross-sectional area of the replasma generation chamber 4.

In addition, for a microwave plasma generator of a type that does not use ECH using an external magnetic field, for example, Japanese Patent Application Laid-Open No. 56-1124
As described in Japanese Patent No. 722, a means for gradually expanding the plasma within the plasma generating section is disclosed. However, this method generates plasma by ionizing it using the microwave electric field of the internal conductor of a coaxial waveguide. Generated on the internal walls of objects. Such plasma contains impurities from the wall surface and there is a lot of loss to the wall surface, so there is a problem that it is difficult to obtain high density and high purity plasma.

It is an object of the present invention to provide microwave plasma processing that solves the problems of the prior art described above and can increase the processing area and improve the processing efficiency without impairing the coupling degree of microwave incidence into the plasma generation chamber. We are in the process of providing equipment.

[Means for solving problems]

In order to achieve the above object, the present invention transmits microwave power generated by a microwave oscillator through a waveguide and introduces it into a plasma generation chamber, generates a magnetic field inside the plasma generation chamber, and uses the microwave and magnetic field to generate a magnetic field. Ions are extracted from the generated plasma into the processing chamber using an ion extraction device.
In a microwave plasma processing device that processes a sample using these ions, the plasma generation chamber is located between the opening to the waveguide and the ion extraction device, with the cross-sectional area of the plasma generation chamber facing toward the opening of the waveguide. It is characterized by having a portion that increases almost continuously from the ion extraction device toward the ion extraction device side.

[For production]

Microwaves transmitted through a waveguide with a predetermined shape have a mode determined by the shape of the waveguide, and if the shape of the waveguide is suddenly changed, the above mode cannot be maintained.
Reflections and losses increase significantly. In the present invention, the plasma generation chamber extracts ions from the opening to the waveguide! 11, there was a part where the cross-sectional area of the plasma generation chamber increased almost continuously from the opening side of the waveguide toward the ion extraction device side. The cross-sectional area can be increased, and ions can be extracted from a wide area.

〔Example〕

Hereinafter, the present invention will be explained based on an illustrated example.

1a) is a sectional view of a microwave plasma processing apparatus according to the embodiment @1 of the present invention, and FIG. c.
- Sectional view along I c, Figure 1 1eil is Figure 1 1al
FIG. 3 is a magnetic field distribution diagram inside the plasma generation chamber of the apparatus shown in FIG. In the figure, parts that are the same as those shown in FIG. 8 are given the same reference numerals, and explanations thereof will be omitted. Reference numeral 15a indicates a plurality of permanent magnets arranged on the same circumference near the entrance window 5, as shown in FIG.
is placed facing the

15b is a plurality of permanent 8 stones arranged on the same circumference adjacent to the permanent magnet 15a and larger than the circumference thereof,
Like the permanent magnet 15a, its south pole faces the plasma generation chamber 4. 15c is a plurality of permanent magnets arranged away from the permanent magnet 15b toward the processing device 9, and includes 8 permanent magnets 15.
The N poles are arranged on the same circumference, which is larger than b, with each N pole facing toward the plasma generation chamber 4. 15d is a plurality of permanent magnets arranged adjacent to the processing device 9 side of the permanent magnet 15C, as shown in FIG.
Plasma generation chamber 4 with each N pole on the same circumference larger than 5C
is placed towards. 16 is each of the above permanent magnets 15a
It is a container configured to be inscribed in ~15d. 17
is an ion extraction magnetic pole provided at the end of the container 16 on the side of the processing device 9, and the plasma electrode m17a in contact with the plasma 6
, an extraction magnetic pole 17b for extracting positive ions from the plasma 6 by applying a negative potential to the plasma magnetic pole 17a.
, and a ground magnetic pole 17c which is set to the ground potential like the processing device 9.

Next, the operation of this embodiment will be explained with reference to the magnetic flux distribution diagram shown in FIG. 1dl. In FIG. 1 d), the horizontal axis represents the a-flux density, and the vertical axis represents the distance in the axial direction of the plasma generation chamber 4. The vacuum exhaust device 12 reduces the entire area to 10"" T.
After creating a main vacuum of approximately 100 torr, the plasma generation chamber 4 is irradiated with microwaves with a required gas such as argon or CF4 filled at 10-3 to 10" Torr, and the filled gas is turned into plasma. Ru.

On the other hand, a magnetic field having a magnetic flux density distribution shown in FIG. 1d) is generated in the plasma generation chamber 4 by each of the permanent magnets 15a to 15d. The magnetic flux density of this magnetic field is such that ions are extracted from the position where the magnetic flux density is maximum. It has a region A that gradually becomes smaller toward the magnetic pole side.

The presence of such a magnetic field causes cyclotron motion of electrons within the plasma 6, causing the electrons to collide with neutral particles and generate ions with relatively low kinetic energy (low ion temperature). The generation efficiency of the plasma 6 is highest in the vicinity where the magnetic flux f1M degree is maximum, and the plasma 6 generated in this vicinity is transported toward the ion extraction magnetic pole 17 by the magnetic flux density gradient in the region A.

Since the container 16 is configured to be inscribed in each of the permanent magnets 15a to 15d, the magnetic flux density near the inner surface of the container 16 is approximately equal on both the microwave incident side and the ion extraction magnetic pole 17 side, and the distances from the wall surface of the container 16 are approximately equal. It is possible to obtain a magnetic flux density that satisfies the ECR conditions in terms of .This makes the plasma generation region gradually wider from the microwave incidence side toward the ion extraction magnetic pole 17, as shown in FIG. This makes it possible to widen the ion extraction area.

The ions extracted from the plasma 6 by the ion extraction magnetic pole 17 are generally positively charged ions 11, and the extracted ions 11 are accelerated and irradiated onto the sample 10, thereby subjecting the sample 10 to necessary processing, For example, pattern processing may be performed by milling, etching, etc.

As described above, in this example, the magnet array radius is made small on the microwave incidence side, and the magnet arrangement radius is made large on the ion extraction magnetic pole side, and the container 16 is configured by being inscribed in each of these magnets. It is possible to widen the ion extraction area without impairing the coupling degree of incident microwaves, increasing the processing area and improving processing efficiency. In addition, it is easy to use rare earth materials as permanent magnets.
It is possible to obtain a magnetic field larger than Tesla, which eliminates the need for a stable DC power supply and cooling device for generating a magnetic field, which is required when using an electromagnetic coil, which in turn reduces costs and occupies less space. A reduction in area can be achieved.

FIG. 2 is a sectional view of a microwave plasma processing apparatus according to a second embodiment of the present invention. In the figure, parts ic that are the same as those shown in FIG. 19a and 19b are electromagnetic coils, and the diameter of the electromagnetic coil 19a on the microwave incidence side is made smaller than the diameter of the electromagnetic coil 19b on the ion extraction magnetic pole 17 side. These electromagnetic coils 19a.

By supplying current to 19b, it is possible to form a magnetic field in which the magnetic flux density distribution near the central axis of the plasma generation chamber gradually decreases from the microwave incidence side toward the ion extraction magnetic pole 17, similar to the Saginomi miM. therefore,
In this embodiment as well, the ion extraction area can be increased and the processing capacity can be improved without impairing the degree of coupling of microwaves incident on the plasma generation chamber.

FIG. 3 is a sectional view of a microwave plasma processing apparatus according to a third embodiment of the present invention. In the figure, the same parts as those shown in FIG.

20 is an electromagnetic coil placed near the microwave incidence port. This electromagnetic coil 20 includes permanent magnets 15a, 1
Forms a magnetic field in the same direction as the magnetic field formed by 5b. fi is supplied. The magnetic field of the electromagnetic coil 20 can maximize the magnetic flux density near the microwave incidence port of the plasma generation chamber 40, thereby suppressing the diffusion loss of the generated plasma in the direction of the microwave incidence window 5 and generating plasma. It is possible to increase the density.

In this embodiment, since an electromagnetic filter is used in combination with the permanent magnet, the magnetic field distribution can be controlled with high accuracy, and the plasma generation efficiency can be increased. The effect of increasing the ion extraction area and improving the processing capacity is the same as that of the first embodiment.

FIG. 4 (al and Ibl are a vertical cross-sectional view and a cross-sectional view of a microwave plasma processing apparatus according to a fourth embodiment of the present invention. In the figure, the same parts as shown in FIG. 1 are designated by the same reference numerals. The explanation will be omitted by adding .In each example of the rabbit,
Although the container 16 constituting the plasma generation chamber 4 had only a truncated conical shape, in this embodiment, a cylindrical container connected to the ion extraction magnetic pole 17 side of the truncated conical container 16 was used. It has a container 21.

22 is a permanent magnet placed around the container 21. FIG. 4 1bl is a sectional view along the line 1yb-4yb of FIG. 4fa), which shows the arrangement and polarity of the permanent magnets 22. 23 is a plasma expansion chamber formed by the container 21. The plasma expansion chamber 23 is in communication with the plasma generation chamber 4.

The polarity of the adjacent permanent magnets 22 is as shown in FIG.
They are arranged to have opposite polarities as shown in b+.

Therefore, near the inner wall surface of the container 21 of the plasma expansion chamber 23, a magnetic field directed toward the adjacent magnet is formed, and this magnetic field can confine the plasma 6 in a position away from the electrical image of the container 21.

In this embodiment, the magnetic field near the center of the plasma expansion chamber 23 is very small, and the plasma density distribution in the radial direction within the plasma expansion chamber 23 is almost uniform.
By arranging the ion extraction magnetic pole 17 at the exit of the plasma expansion chamber 23, it is possible not only to achieve the same effect as in the first embodiment but also to obtain an ion beam with a uniform distribution, which in turn improves the precision of the plasma processing apparatus. It is also possible to obtain good and uniform processing characteristics.

FIG. 5 is a sectional view of a microwave plasma processing apparatus according to a fifth embodiment of the present invention. In the figure, the same parts as those shown in FIG. 1a) are given the same reference numerals, and their explanation will be omitted.

A plurality of permanent magnets 25 are magnetized in the axial direction, and a plurality of permanent magnets are arranged outside the plasma generation chamber so that their magnetic poles coincide in the axial direction. By using such a permanent magnet 25, this embodiment has the same effect as the first embodiment, can maximize the characteristics of the permanent magnet, and is easy to install. I by reducing the radial dimension
It also has the effect of

FIG. 6 is a sectional view of a microwave plasma processing apparatus according to a sixth embodiment of the present invention. In the figure, parts that are the same as those shown in FIG.

27 is a semicircular or U-shaped permanent magnet. this eternity 8
A plurality of stones 27 are arranged around the outer periphery of the plasma generation chamber 4, and each permanent magnet 27 is magnetized in an arcuate direction and arranged in such a way that the polarity of each of their magnetic poles coincides in the axial direction. This embodiment has the same effect as the first embodiment, and since the magnetic field created by the permanent magnet 27 is closed within the magnet outside the plasma generation chamber 4, leakage magnetic flux is reduced and the magnetic field inside the plasma generation chamber is It also has the effect of making it possible to increase the strength of the plasma, thereby increasing the plasma generation efficiency.

Figure 7 shows the seventh fruit of the present invention! ! FIG. 2 is a sectional view of a microwave plasma processing apparatus according to IIJ. In the figure, parts that are the same as those shown in FIG. Reference numeral 29 denotes a permanent magnet arranged at an angle around the outer periphery of the plasma generation chamber 4. These permanent magnets 29 are magnetized in the width (or thickness) direction so that the magnetization direction is in the radial direction, and are arranged so that adjacent permanent magnets have opposite polarities. It is clear that the magnetic flux density of the magnetic field formed by these permanent magnets 29 gradually decreases from the microwave incidence side to the ion extraction magnetic pole 17 side, as in each of the Sagi embodiments, and as shown in FIG. As shown in bl, it is large near the wall of the plasma generation chamber and gradually becomes smaller toward the center of the plasma generation chamber 4.In such a magnetic flux density distribution, the strength of the magnet is sufficiently increased to obtain EC.
Plasma can be efficiently generated by providing a magnetic flux density that satisfies the R condition. And plasma generation chamber 4
The plasma generated near the wall of the ion extraction magnetic pole 1 moves toward the center of the plasma generation chamber 4 due to the gradient of the magnetic field.
7 will be transported.

This embodiment has the same effect as the WCL embodiment and also has the effect of being able to extract a uniform ion beam.

〔Effect of the invention〕

As described above, in the present invention, between the microwave introduction section and the ion extraction magnetic pole, the plasma generation chamber is formed into a portion whose cross-sectional area continuously increases from the microwave introduction section side to the ion extraction magnetic pole side. Since the plasma generating chamber is configured to have the following characteristics, the ion extraction area can be increased without impairing the degree of coupling of microwaves incident on the plasma generation chamber, thereby increasing the processing area and improving processing efficiency.

[Brief explanation of drawings]

FIG. 1 [a) k1 Microwave plasma treatment according to the first embodiment of the present invention! Cross-sectional view of It, Figure 1 1dl, I
cl are the lines lb-1b shown in FIG. 1 1a), respectively;
A cross-sectional view along Ic-1c, Fig. 1 1dl is Fig. 1 ta
>K The magnetic flux density distribution diagrams of the device shown in FIGS. 2 and 3 are respectively the 2nd. FIG. 4 is a cross-sectional view of a microwave plasma processing apparatus according to a third embodiment of the present invention (at is a cross-sectional view of a microwave plasma processing apparatus according to a fourth embodiment of the present invention, and FIG. Line 1'y b shown in
-1yb A sectional view of a microwave plasma processing apparatus. FIG. 8 is a sectional view of a conventional microwave plasma processing apparatus. 1...Microwave oscillator, 2...Waveguide, 4...Plasma generation chamber, 6...Plasma, 9... Processing device, 10... Sample, 15a to 15L 25127.29... Permanent magnet, 16... Container, 17... Ion extraction magnetic pole, 19 a, 19 b , 20...
...Electromagnetic coil. 6: Push-sun 17: Ion drawer saliva 9
:M11sll Figure 7! Figure 8

Claims (1)

[Claims] 1. A microwave oscillator, a waveguide for transmitting microwave power generated by the microwave oscillator, a plasma generation chamber having an opening to the waveguide, and a magnetic field within the plasma generation chamber. In the microwave plasma processing apparatus, the plasma generation chamber includes a magnetic field generation device that generates a magnetic field, an ion extraction device that extracts ions from the plasma generated in the plasma generation chamber, and a processing chamber that utilizes the extracted ions. , between the opening to the waveguide and the ion extraction device, a portion where the cross-sectional area of the plasma generation chamber increases almost continuously from the opening of the waveguide toward the ion extraction device; A microwave plasma processing apparatus comprising: 2. The microwave plasma processing apparatus according to claim 1, wherein the magnetic field generating device is an electromagnetic coil arranged along the outer surface of the plasma generation chamber. 3. The microwave plasma according to claim 1, wherein the magnetic field generating device is a permanent magnet arranged so as to form an axial magnetic field along the outer surface of the plasma generation chamber. Processing equipment. 4. In claim 3, the permanent magnet is
A microwave plasma processing apparatus characterized in that magnetic poles adjacent to each other along the circumferential direction of the outer periphery of the plasma generation chamber are arranged to have the same polarity. 5. In claim 3, the permanent magnet is:
A microwave plasma processing apparatus characterized in that magnetic poles adjacent to each other along the circumferential direction of the outer periphery of the plasma generation chamber are arranged so as to have opposite polarities. 6. In claim 1, the plasma generation chamber has a plasma storage chamber having an area larger than the opening at the opening on the side of the ion extraction device, and a plasma storage chamber having opposite magnetic poles adjacent along the outer periphery of the plasma storage chamber. A microwave plasma processing apparatus characterized by being provided with permanent magnets arranged so as to be polarized.